This invention relates to the administration of drugs to a patient via inhalation through the oral and/or nasal passages, and more especially to a device which propels a uniform dosage of finely divided medicament into the lungs through the aforementioned passages.
In the past, administration of medicaments for the alleviation of ailments of the lungs has been carried out using plastic squeeze bottles or aerosol cans to deliver drugs through the oral and/or nasal cavities. Devices of this type have not been entirely satisfactory because they do not allow the user to properly control the medicament concentration or dosage. Furthermore, significant problems arise as a result of the variation in particle size of the medicament spray delivered from these devices. Thus, it is not always possible with these devices to dispense a medicament in the form of very fine and uniform particle size or mist which can be readily inhaled by the user. Sonic generators have proven to be the only truly effective devices for accomplishing complete control of both medicament dosage and particle size; however, these are extremely large and can be used only in a hospital, doctor's office, clinic, etc. There have also been attempts to provide smaller, pocket-sized inhalation devices which may be used in any location to supply the necessary medication. Many of these personal sized devices are based upon aerosol principles (see for example, U.S. Pats. No. 3,183,907, No. 3,456,645, and No. 3,456,646) and of necessity suffer from the aforementioned disadvantages associated with aerosolized atomizers. More recent endeavors in the area of pocket size atomizers are exemplified by U.S. Pats. Nos. 3,507,277 and 3,518,992 wherein the medicament is placed in the inhaler in capsulized form, made of gelatin or other material, and thereafter the capsule is perforated in situ to render the medicament available immediately prior to its contemplated use. The user then inhales through the device which causes an internally contained propeller, as well as the punctured capsule, to rotate thereby dispensing the medicament from the device and into the oral or nasal passages of the user. While these latter type of devices may solve the heretofore mentioned medicament dosage and particle size problems, they too are rendered not wholly effective because typically those people having ailments necessitating the subject medication, as for example asthmatic patients, cannot efficiently draw air through their oral or nasal passages, and, as a result, they often cannot administer to themselves the entire medicament dosage. In fact, those persons most in need of the drug are those who are least able to draw air, and hence medicament, through the device.